{"markup":"\u003C?xml version=\u00221.0\u0022 encoding=\u0022UTF-8\u0022 ?\u003E\n \u003Chtml version=\u0022HTML+RDFa+MathML 1.1\u0022\n xmlns:content=\u0022http:\/\/purl.org\/rss\/1.0\/modules\/content\/\u0022\n xmlns:dc=\u0022http:\/\/purl.org\/dc\/terms\/\u0022\n xmlns:foaf=\u0022http:\/\/xmlns.com\/foaf\/0.1\/\u0022\n xmlns:og=\u0022http:\/\/ogp.me\/ns#\u0022\n xmlns:rdfs=\u0022http:\/\/www.w3.org\/2000\/01\/rdf-schema#\u0022\n xmlns:sioc=\u0022http:\/\/rdfs.org\/sioc\/ns#\u0022\n xmlns:sioct=\u0022http:\/\/rdfs.org\/sioc\/types#\u0022\n xmlns:skos=\u0022http:\/\/www.w3.org\/2004\/02\/skos\/core#\u0022\n xmlns:xsd=\u0022http:\/\/www.w3.org\/2001\/XMLSchema#\u0022\n xmlns:mml=\u0022http:\/\/www.w3.org\/1998\/Math\/MathML\u0022\u003E\n \u003Chead\u003E\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022\/\/cdn.jsdelivr.net\/qtip2\/2.2.1\/jquery.qtip.min.js\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/jeb.biologists.org\/sites\/default\/files\/js\/js_-MZHQc7Ran_h4OtcC-HT9BulQMedaos1-NFBhT1razc.js\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022\u003E\n\u003C!--\/\/--\u003E\u003C![CDATA[\/\/\u003E\u003C!--\nwindow.MathJax = { menuSettings: { zoom: \u0022Click\u0022 } };\n\/\/--\u003E\u003C!]]\u003E\n\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/jeb.biologists.org\/sites\/default\/files\/js\/js_gPqjYq7fqdMzw8-29XWQIVoDSWTmZCGy9OqaHppNxuQ.js\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022\u003E\n\u003C!--\/\/--\u003E\u003C![CDATA[\/\/\u003E\u003C!--\n(function(i,s,o,g,r,a,m){i[\u0022GoogleAnalyticsObject\u0022]=r;i[r]=i[r]||function(){(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)})(window,document,\u0022script\u0022,\u0022\/\/www.google-analytics.com\/analytics.js\u0022,\u0022ga\u0022);ga(\u0022create\u0022, \u0022UA-23555390-2\u0022, {\u0022cookieDomain\u0022:\u0022auto\u0022});ga(\u0022set\u0022, \u0022anonymizeIp\u0022, true);ga(\u0022set\u0022, \u0022page\u0022, location.pathname + location.search + location.hash);ga(\u0022send\u0022, \u0022pageview\u0022);ga(\u0027create\u0027, \u0027UA-189672-18\u0027, \u0027auto\u0027, {\u0027name\u0027: \u0027hwTracker\u0027});\r\nga(\u0027set\u0027, \u0027anonymizeIp\u0027, true);\nga(\u0027hwTracker.send\u0027, \u0027pageview\u0027);\n\/\/--\u003E\u003C!]]\u003E\n\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022\u003E\n\u003C!--\/\/--\u003E\u003C![CDATA[\/\/\u003E\u003C!--\njQuery.extend(Drupal.settings, {\u0022basePath\u0022:\u0022\\\/\u0022,\u0022pathPrefix\u0022:\u0022\u0022,\u0022highwire\u0022:{\u0022ac\u0022:{\u0022\\\/jexbio\\\/206\\\/19\\\/3327.atom\u0022:{\u0022access\u0022:{\u0022full\u0022:true},\u0022pisa_id\u0022:\u0022\u0022,\u0022apath\u0022:\u0022\\\/jexbio\\\/206\\\/19\\\/3327.atom\u0022,\u0022jcode\u0022:\u0022jexbio\u0022}},\u0022quick_nav\u0022:{\u0022nav_down_icon\u0022:\u0022icon-caret-down\u0022,\u0022nav_up_icon\u0022:\u0022icon-caret-up\u0022,\u0022nav_class\u0022:\u0022mobile-only float-me-right\u0022},\u0022processed\u0022:[\u0022highwire_math\u0022],\u0022markup\u0022:[{\u0022requested\u0022:\u0022long\u0022,\u0022variant\u0022:\u0022full-text\u0022,\u0022view\u0022:\u0022full\u0022,\u0022pisa\u0022:\u0022jexbio;206\\\/19\\\/3327\u0022}],\u0022trendmd\u0022:{\u0022trendmd-suggestions\u0022:\u0022{\\u0022element\\u0022:\\u0022#trendmd-suggestions\\u0022,\\u0022track_id\\u0022:\\u0022null\\u0022}\u0022}},\u0022instances\u0022:\u0022{\\u0022highwire_abstract_tooltip\\u0022:{\\u0022content\\u0022:{\\u0022text\\u0022:\\u0022\\u0022},\\u0022style\\u0022:{\\u0022tip\\u0022:{\\u0022width\\u0022:20,\\u0022height\\u0022:20,\\u0022border\\u0022:1,\\u0022offset\\u0022:0,\\u0022corner\\u0022:true},\\u0022classes\\u0022:\\u0022qtip-custom hw-tooltip hw-abstract-tooltip qtip-shadow qtip-rounded\\u0022,\\u0022classes_custom\\u0022:\\u0022hw-tooltip hw-abstract-tooltip\\u0022},\\u0022position\\u0022:{\\u0022at\\u0022:\\u0022right center\\u0022,\\u0022my\\u0022:\\u0022left center\\u0022,\\u0022viewport\\u0022:true,\\u0022adjust\\u0022:{\\u0022method\\u0022:\\u0022shift\\u0022}},\\u0022show\\u0022:{\\u0022event\\u0022:\\u0022mouseenter click \\u0022,\\u0022solo\\u0022:true},\\u0022hide\\u0022:{\\u0022event\\u0022:\\u0022mouseleave \\u0022,\\u0022fixed\\u0022:1,\\u0022delay\\u0022:\\u0022100\\u0022}},\\u0022highwire_author_tooltip\\u0022:{\\u0022content\\u0022:{\\u0022text\\u0022:\\u0022\\u0022},\\u0022style\\u0022:{\\u0022tip\\u0022:{\\u0022width\\u0022:15,\\u0022height\\u0022:15,\\u0022border\\u0022:1,\\u0022offset\\u0022:0,\\u0022corner\\u0022:true},\\u0022classes\\u0022:\\u0022qtip-custom hw-tooltip hw-author-tooltip qtip-shadow qtip-rounded\\u0022,\\u0022classes_custom\\u0022:\\u0022hw-tooltip hw-author-tooltip\\u0022},\\u0022position\\u0022:{\\u0022at\\u0022:\\u0022top center\\u0022,\\u0022my\\u0022:\\u0022bottom center\\u0022,\\u0022viewport\\u0022:true,\\u0022adjust\\u0022:{\\u0022method\\u0022:\\u0022\\u0022}},\\u0022show\\u0022:{\\u0022event\\u0022:\\u0022mouseenter \\u0022,\\u0022solo\\u0022:true},\\u0022hide\\u0022:{\\u0022event\\u0022:\\u0022mouseleave \\u0022,\\u0022fixed\\u0022:1,\\u0022delay\\u0022:\\u0022100\\u0022}},\\u0022highwire_reflinks_tooltip\\u0022:{\\u0022content\\u0022:{\\u0022text\\u0022:\\u0022\\u0022},\\u0022style\\u0022:{\\u0022tip\\u0022:{\\u0022width\\u0022:15,\\u0022height\\u0022:15,\\u0022border\\u0022:1,\\u0022mimic\\u0022:\\u0022top center\\u0022,\\u0022offset\\u0022:0,\\u0022corner\\u0022:true},\\u0022classes\\u0022:\\u0022qtip-custom hw-tooltip hw-ref-link-tooltip qtip-shadow qtip-rounded\\u0022,\\u0022classes_custom\\u0022:\\u0022hw-tooltip hw-ref-link-tooltip\\u0022},\\u0022position\\u0022:{\\u0022at\\u0022:\\u0022bottom left\\u0022,\\u0022my\\u0022:\\u0022top left\\u0022,\\u0022viewport\\u0022:true,\\u0022adjust\\u0022:{\\u0022method\\u0022:\\u0022flip\\u0022}},\\u0022show\\u0022:{\\u0022event\\u0022:\\u0022mouseenter \\u0022,\\u0022solo\\u0022:true},\\u0022hide\\u0022:{\\u0022event\\u0022:\\u0022mouseleave \\u0022,\\u0022fixed\\u0022:1,\\u0022delay\\u0022:\\u0022100\\u0022}}}\u0022,\u0022qtipDebug\u0022:\u0022{\\u0022leaveElement\\u0022:0}\u0022,\u0022googleanalytics\u0022:{\u0022trackOutbound\u0022:1,\u0022trackMailto\u0022:1,\u0022trackDownload\u0022:1,\u0022trackDownloadExtensions\u0022:\u00227z|aac|arc|arj|asf|asx|avi|bin|csv|doc(x|m)?|dot(x|m)?|exe|flv|gif|gz|gzip|hqx|jar|jpe?g|js|mp(2|3|4|e?g)|mov(ie)?|msi|msp|pdf|phps|png|ppt(x|m)?|pot(x|m)?|pps(x|m)?|ppam|sld(x|m)?|thmx|qtm?|ra(m|r)?|sea|sit|tar|tgz|torrent|txt|wav|wma|wmv|wpd|xls(x|m|b)?|xlt(x|m)|xlam|xml|z|zip\u0022,\u0022trackColorbox\u0022:1,\u0022trackUrlFragments\u0022:1},\u0022ajaxPageState\u0022:{\u0022js\u0022:{\u0022\\\/\\\/cdn.jsdelivr.net\\\/qtip2\\\/2.2.1\\\/jquery.qtip.min.js\u0022:1,\u0022sites\\\/all\\\/modules\\\/highwire\\\/highwire\\\/plugins\\\/highwire_markup_process\\\/js\\\/highwire_article_reference_popup.js\u0022:1,\u0022sites\\\/all\\\/modules\\\/highwire\\\/highwire\\\/plugins\\\/highwire_markup_process\\\/js\\\/highwire_quick_nav.js\u0022:1,\u0022sites\\\/all\\\/modules\\\/highwire\\\/highwire\\\/plugins\\\/highwire_markup_process\\\/js\\\/highwire_at_symbol.js\u0022:1,\u00220\u0022:1,\u0022sites\\\/all\\\/modules\\\/contrib\\\/google_analytics\\\/googleanalytics.js\u0022:1,\u00221\u0022:1}}});\n\/\/--\u003E\u003C!]]\u003E\n\u003C\/script\u003E\n\u003Clink type=\u0022text\/css\u0022 rel=\u0022stylesheet\u0022 href=\u0022\/\/jeb.biologists.org\/sites\/default\/files\/advagg_css\/css__uXgUByez87OKDsgffPHe7u5qNUzr7zOnqWrSJ87THKk__RR-QNYl6SsTObm37M1MaRCUwwzIP19wUZLcqO_pRc1Q__VGhDWvAlEgBQ4U3sicAk2jL62sVT0mh15eL_yxy94_w.css\u0022 media=\u0022all\u0022 \/\u003E\n\u003Clink type=\u0022text\/css\u0022 rel=\u0022stylesheet\u0022 href=\u0022\/\/cdn.jsdelivr.net\/qtip2\/2.2.1\/jquery.qtip.min.css\u0022 media=\u0022all\u0022 \/\u003E\n\u003Clink type=\u0022text\/css\u0022 rel=\u0022stylesheet\u0022 href=\u0022\/\/jeb.biologists.org\/sites\/default\/files\/advagg_css\/css__14LtxqLbXLYbBfVMMQ9Q34-c_XuRCLysSbYzec2Yg7c__Z0uQp4m9tFiEZP0bFEgoD4CsR3FkQHIP2WAIdv-eq9Y__VGhDWvAlEgBQ4U3sicAk2jL62sVT0mh15eL_yxy94_w.css\u0022 media=\u0022all\u0022 \/\u003E\n\u003Clink rel=\u0027stylesheet\u0027 type=\u0027text\/css\u0027 href=\u0027\/sites\/all\/modules\/contrib\/panels\/plugins\/layouts\/onecol\/onecol.css\u0027 \/\u003E\u003C\/head\u003E\u003Cbody\u003E\u003Cdiv class=\u0022panels-ajax-tab-panel panels-ajax-tab-panel-jnl-template-cob-tab-art\u0022\u003E\u003Cdiv class=\u0022panel-display panel-1col clearfix\u0022 \u003E\n \u003Cdiv class=\u0022panel-panel panel-col\u0022\u003E\n \u003Cdiv\u003E\u003Cdiv class=\u0022panel-pane pane-highwire-markup article-heading\u0022 \u003E\n \n \n \n \u003Cdiv class=\u0022pane-content\u0022\u003E\n \u003Cdiv class=\u0022highwire-markup\u0022\u003E\u003Cdiv xmlns=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022 id=\u0022content-block-markup\u0022 data-highwire-cite-ref-tooltip-instance=\u0022highwire_reflinks_tooltip\u0022 xmlns:xhtml=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003E\u003Cdiv class=\u0022article fulltext-view\u0022\u003E\u003Cspan class=\u0022highwire-journal-article-marker-start\u0022\u003E\u003C\/span\u003E\u003Cdiv class=\u0022section abstract\u0022 id=\u0022abstract-1\u0022\u003E\u003Ch2\u003ESUMMARY\u003C\/h2\u003E\n \u003Cp id=\u0022p-1\u0022\u003EThe bulbus arteriosus of the teleost heart possesses a static inflation\ncurve that is r-shaped over the \u003Cem\u003Ein vivo\u003C\/em\u003E pressure range. To examine\nthe possible significance of this in living animals, we recorded arterial\nblood pressure from anaesthetized yellowfin tuna and utilized a video\ndimensional analyser to simultaneously record changes in bulbar diameter. By\nplotting the changes in pressure against the changes in diameter, it was\npossible to create dynamic pressure-diameter (P-D) loops as well as calculate\nthe instantaneous volume changes within the bulbus. The dynamic P-D loops\nshowed the same features exhibited by static inflation. When nearly empty, a\nsmall stroke volume caused a large increase in blood pressure, while around\nsystolic pressure large changes in volume resulted in small changes in\npressure. We conclude that these features allow the bulbus to maintain ventral\naortic flows and pressures over a large range of volumes.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cul class=\u0022kwd-group KWD\u0022\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/search\/%20text_abstract_title%3Abulbus%2Barteriosus%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-bulbus-arteriosus\u0022 rel=\u0022nofollow\u0022\u003Ebulbus arteriosus\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/search\/%20text_abstract_title%3AP-D%2Bloop%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-p-d-loop\u0022 rel=\u0022nofollow\u0022\u003EP-D loop\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/search\/%20text_abstract_title%3Ar-shaped%2Bcurve%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-r-shaped-curve\u0022 rel=\u0022nofollow\u0022\u003Er-shaped curve\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/search\/%20text_abstract_title%3Avideo%2Bdimensional%2Banalysis%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-video-dimensional-analysis\u0022 rel=\u0022nofollow\u0022\u003Evideo dimensional analysis\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca href=\u0022\/search\/%20text_abstract_title%3Atuna%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-tuna\u0022 rel=\u0022nofollow\u0022\u003Etuna\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003E\u003Ca xmlns:default=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022 href=\u0022\/search\/%20text_abstract_title%3AThunnus.%20text_abstract_title_flags%3Amatch-phrase%20sort%3Apublication-date\u0022 class=\u0022hw-term hw-article-keyword hw-article-keyword-thunnus\u0022 rel=\u0022nofollow\u0022\u003E\u003Cem xmlns:default=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003EThunnus\u003C\/em\u003E.\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-1\u0022\u003E\n \u003Ch2\u003EIntroduction\u003C\/h2\u003E\n \u003Cp id=\u0022p-2\u0022\u003EThe smoothness of flow and pressure in the ventral aorta of teleosts is due\nto the presence of a large central compliance that is the product of elastic\nand resistive elements downstream of the heart. While the resistance of the\ngills is only about 30-50% of the total peripheral resistance, the ventral\naorta and branchial arteries are short, resulting in a small total compliance\nof the central arterial circulation. The bulbus arteriosus, the most anterior\nof the four chambers of the teleost heart, greatly increases central vascular\ncompliance, largely subserving the Windkessel functions of the whole mammalian\narterial tree (\u003Ca id=\u0022xref-ref-23-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-23\u0022\u003Evon Skramlick,\n1935\u003C\/a\u003E; cited in \u003Ca id=\u0022xref-ref-17-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-17\u0022\u003EMott,\n1950\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-21-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-21\u0022\u003ESatchell,\n1971\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-22-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-22\u0022\u003EStevens et al.,\n1972\u003C\/a\u003E; \u003Ca id=\u0022xref-ref-15-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-15\u0022\u003ELicht and Harris,\n1973\u003C\/a\u003E; Jones et al.,\n\u003Ca id=\u0022xref-ref-13-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-13\u0022\u003E1974\u003C\/a\u003E,\n\u003Ca id=\u0022xref-ref-14-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-14\u0022\u003E1993\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-18-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-18\u0022\u003EPriede, 1976\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-8-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-8\u0022\u003EFarrell, 1979\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-24-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-24\u0022\u003EWatson and Cobb, 1979\u003C\/a\u003E;\nBenjamin et al., \u003Ca id=\u0022xref-ref-1-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-1\u0022\u003E1983\u003C\/a\u003E,\n\u003Ca id=\u0022xref-ref-2-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-2\u0022\u003E1984\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-20-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-20\u0022\u003ESanter, 1985\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-5-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-5\u0022\u003EBushnell et al., 1992\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-12-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-12\u0022\u003EJones, 1999\u003C\/a\u003E). In a Windkessel,\nthe arteries expand with each heartbeat and recoil elastically, causing the\nhighly pulsatile inflow to become relatively smooth in the periphery. How a\nrelatively short bulbus mimics these effects of a longer arterial tree has\nnever been explained.\u003C\/p\u003E\n \u003Cp id=\u0022p-3\u0022\u003ELike an artery, the bulbus is composed of elastin, collagen and smooth\nmuscle; however, it is highly modified, resulting in specialized inflation\nproperties (\u003Ca id=\u0022xref-ref-4-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBraun et al.,\n2003\u003C\/a\u003E). Over the \u003Cem\u003Ein vivo\u003C\/em\u003E pressure range, an artery has a\nJ-shaped P-V (pressure-volume) loop, while the bulbus has an r-shaped P-V\nloop. The bulbar curve can be broken into distinctive stages: (1) a sharp\ninitial rise in pressure for a relatively small volume change and (2) a\nplateau stage where the bulbus is largely unaffected by even large changes in\nvolume. There is even some evidence to suggest that there is a third stage of\nthe bulbar inflation (\u003Ca id=\u0022xref-ref-4-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBraun et al.,\n2003\u003C\/a\u003E); when greatly distended, the bulbar material rapidly\nincreases in stiffness.\u003C\/p\u003E\n \u003Cp id=\u0022p-4\u0022\u003EStage 1 is due to the relationship between the wall tension, pressure and\nvolume of the bulbus, as described by the Law of Laplace. The bulbar lumen is\nvery small at low pressure and therefore bulbar expansion requires a large\ninitial pressure increment. Stage 2 is a result of the specialized material\nproperties of the bulbus. The bulbar wall has a very high elastin:collagen\nratio and is almost entirely composed of novel elastin (low hydrophobicity,\nhigh solubility) aligned in a novel manner (loose fibrils, no lamellae). These\nmodifications produce very low wall stiffness and the ability to undergo large\nstrain changes and result in the compliance of the plateau. At large\nextensions, stiff adventitial collagen is recruited to resist the expansion of\nthe bulbus.\u003C\/p\u003E\n \u003Cp id=\u0022p-5\u0022\u003EKnowing the causes of the strange bulbar P-V loop is an important first\nstep in understanding how the bulbus works. However, in order to make\ninferences based on the \u003Cem\u003Ein vitro\u003C\/em\u003E inflation curve, it is vital that\nthe bulbus shows similar traits \u003Cem\u003Ein vivo.\u003C\/em\u003E To this end, \u003Cem\u003Ein\nvivo\u003C\/em\u003E changes in pressure and bulbar diameter during normal beating in\nanaesthetised yellowfin tuna were recorded using video dimensional analysis\n(VDA) and pressure recordings.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-2\u0022\u003E\n \u003Ch2\u003EMaterials and methods\u003C\/h2\u003E\n \u003Cp id=\u0022p-6\u0022\u003EThe experiments were performed on the bulbi of five \u003Cem\u003EThunnus\nalbacares\u003C\/em\u003E L. (1.12\u00b10.32 kg) that were held in large outdoor tanks\nat the National Marine Fisheries Service Kewalo Research Facility in Honolulu,\nHI, USA. The water temperature in the holding tanks was 25\u00b0C.\u003C\/p\u003E\n \u003Cp id=\u0022p-7\u0022\u003EYellowfin tuna were anaesthetized using 0.2 g l\u003Csup\u003E-1\u003C\/sup\u003E ethyl p-amino\nbenzoate and equimolar NaHCO\u003Csub\u003E3\u003C\/sub\u003E. Following anaesthesia, the fish were\nplaced supine in a chamois leather cradle. A hose running aerated seawater was\nplaced in the mouth of the anesthetized fish in order to simulate ram\nventilation. A midline incision was made along the ventral surface to expose\nthe pericardial cavity. The pericardium was opened and the heart exposed.\nDuring the experiment, anesthesia was maintained with Saffan (3 mg\nkg\u003Csup\u003E-1\u003C\/sup\u003E intra-arterially; Glaxovet, Harefield, UK). To decrease heart\nrate, water flow over the gills was stopped for several seconds.\u003C\/p\u003E\n \u003Cp id=\u0022p-8\u0022\u003EArterial blood pressure was measured through a cannula inserted into the\nbulbus and connected to a Unonics model P-106 pressure transducer (Wayland,\nMA, USA) (\u003Ca id=\u0022xref-fig-1-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFig. 1\u003C\/a\u003E). Pop tests\nestablished the frequency response of the system to be 32 Hz, with damping\nbeing 0.12 of critical damping (\u003Ca id=\u0022xref-ref-10-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-10\u0022\u003EJones,\n1970\u003C\/a\u003E). Changes in the diameter of the bulbus during systole and\ndiastole were measured using a video dimension analyzer (VDA; Instrumentation\nfor Physiology and Medicine, model 303). This system consists of a video\ncamera, a video processor and a monitor. The camera was focused on the bulbus,\nand the signal fed through the processor. The VDA utilizes the video signal to\ngive a DC voltage that is proportional to the distance between two selected\ncontrast boundaries on the monitor. The VDA `window\u0027\n(\u003Ca id=\u0022xref-fig-1-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFig. 1\u003C\/a\u003E) was used to track the\nmovement of the outside surface of the bulbus as it expanded and contracted\nduring systole and diastole. By calibrating the voltage generated, dynamic\ndimensional changes were recorded. The VDA has a 15 Hz low-pass RC filter on\nthe output signal, which introduces 180\u00b0 of phase delay at 15 Hz.\nAppropriate corrections were applied to the diameter traces. For a more\nin-depth explanation of the VDA, see Fung\n(\u003Ca id=\u0022xref-ref-9-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-9\u0022\u003E1981\u003C\/a\u003E). Voltages and pressures\nwere collected and stored using DASYLAB (Dasytec USA, Amherst, NH, USA).\u003C\/p\u003E\n \u003Cp id=\u0022p-9\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F1\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F1.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022A yellowfin tuna used in the video dimensional analysis (VDA) study showing the bulbus in relation to the ventricle within the pericardial cavity during diastole and systole. The catheter used to record pressure entered the bulbus ventrally. The VDA window was aligned with the bulbus so that from diastole to systole the black portion of the window followed the edges of the bulbus during a heartbeat. Length, as well as width, changed with each beat of the heart.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;A yellowfin tuna used in the video dimensional analysis (VDA) study showing the bulbus in relation to the ventricle within the pericardial cavity during diastole and systole. The catheter used to record pressure entered the bulbus ventrally. The VDA window was aligned with the bulbus so that from diastole to systole the black portion of the window followed the edges of the bulbus during a heartbeat. Length, as well as width, changed with each beat of the heart.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 1.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F1.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 1.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F1.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F1.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 1.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F1.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079120\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022 xmlns:xhtml=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 1.\u003C\/span\u003E \n \u003Cp id=\u0022p-10\u0022 class=\u0022first-child\u0022\u003EA yellowfin tuna used in the video dimensional analysis (VDA) study showing\nthe bulbus in relation to the ventricle within the pericardial cavity during\ndiastole and systole. The catheter used to record pressure entered the bulbus\nventrally. The VDA window was aligned with the bulbus so that from diastole to\nsystole the black portion of the window followed the edges of the bulbus\nduring a heartbeat. Length, as well as width, changed with each beat of the\nheart.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-11\u0022\u003EFollowing dynamic recordings of heart beats from tuna, static \u003Cem\u003Ein\nvivo\u003C\/em\u003E inflations of the bulbi were performed. The proximal ventral aorta\nand the bulbo-ventricular junction were ligated, and a T-junction was inserted\ninto the pressure catheter to allow simultaneous bulbar inflation and pressure\nmeasurement. Measured volumes of saline (25\u00b0C) were injected into the\nbulbus, and the resultant pressure signal was amplified and recorded using\nDASYLAB software. Cycles of inflation and deflation were performed until\nconsistent results were seen. Preconditioning usually required 5-10 cycles.\nThese initial cycles were discarded. Each experiment consisted of 8-15 trials,\nand results from any trials in which a loss of more than 5% of the injected\nsaline occurred were not used. After preconditioning, the data were recorded\nand plotted as pressure (kPa) \u003Cem\u003Eversus\u003C\/em\u003E volume (ml or \u03bcl). By\nsimultaneously measuring the diameter changes due to each injection of fluid,\nit was also possible to create a plot of pressure \u003Cem\u003Eversus\u003C\/em\u003E diameter.\nLinear regressions of the curves yielded calibration curves describing the\ninteractions between injected volume and diameter. Due to the differences in\ndimension along the bulbus, the dynamic and static measurements must be taken\nfrom the same locations. This was not the case for all observations, and,\ntherefore, calibration curves could not be calculated for all recordings of\npressure and diameter. These recordings of pressure and diameter were analyzed\nusing Microsoft EXCEL.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-3\u0022\u003E\n \u003Ch2\u003EResults\u003C\/h2\u003E\n \u003Cdiv id=\u0022sec-4\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003ELongitudinal and circumferential strains\u003C\/h3\u003E\n \u003Cp id=\u0022p-12\u0022\u003EThe maximal longitudinal and circumferential strains recorded with the VDA\noccurred during static inflations of the bulbus. The stroke volume of\nyellowfin tuna is in the range of 0.65-1.00 ml\n(\u003Ca id=\u0022xref-ref-14-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-14\u0022\u003EJones et al., 1993\u003C\/a\u003E) for the\nmass of animals used in these experiments. The bulbus was inflated with 2.5 ml\nof fluid. Maximal static circumferential strain was 0.47, while maximal static\nlongitudinal strain was 0.48.\u003C\/p\u003E\n \u003Cp id=\u0022p-13\u0022\u003EWhen the heart was beating normally [i.e. heart rate approximately 1 Hz,\npeak systolic pressure around 9.5-13.5 kPa and pulse pressure in the range of\n5-6.5 kPa(\u003Ca id=\u0022xref-ref-14-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-14\u0022\u003EJones et al.,\n1993\u003C\/a\u003E)], the range of dynamic circumferential strains was\n0.25-0.38. Ventricular movements moved the position of the bulbus within the\npericardial cavity so that finding the dynamic longitudinal range of strain\nwas not possible.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003Cdiv id=\u0022sec-5\u0022 class=\u0022subsection\u0022\u003E\n \u003Ch3\u003EStatic and dynamic P-V loops\u003C\/h3\u003E\n \u003Cp id=\u0022p-14\u0022\u003EThe VDA followed the walls of the yellowfin tuna bulbus during both systole\nand diastole and allowed mapping of dimensional changes associated with each\nheartbeat (\u003Ca id=\u0022xref-fig-1-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFig. 1\u003C\/a\u003E).\n\u003Ca id=\u0022xref-fig-2-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2A\u003C\/a\u003E compares the\ndimensional and pressure changes occurring during a single heartbeat. The\nrapid increase in pressure resulted in a sharp increase in diameter. Systolic\npressure of 9.3 kPa gradually declined to 4 kPa, while diameter initially fell\nvery rapidly, followed by a smoother decline that more closely followed the\nfall in pressure. By plotting pressure against diameter for the heartbeat in\n\u003Ca id=\u0022xref-fig-2-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2A\u003C\/a\u003E, a pressure-diameter\n(P-D) loop was generated (\u003Ca id=\u0022xref-fig-2-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig.\n2B\u003C\/a\u003E),showing the inflation behaviour of the bulbus under \u003Cem\u003Ein\nvivo\u003C\/em\u003E conditions. When this dynamic P-D loop was compared with a P-D loop\nproduced using the static inflation technique, the dynamic and static\nbehaviours matched well. In both cases, the slope initially rose sharply,\nfollowed by a levelling off as the bulbus reached the plateau phase of the\ninflation.\u003C\/p\u003E\n \u003Cp id=\u0022p-15\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F2\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F2.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna. (B) Comparison of static and dynamic pressure-diameter (P-D) loops. The dynamic trace (green) was created by plotting pressure against diameter for the heartbeat in A and is superimposed on a P-D curve (black) created by a bulbar inflation from a syringe, post mortem. Arrows indicate the clockwise or anticlockwise cycling of the loop. (Diameter ratio is the diameter divided by the initial diameter.)\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna. (B) Comparison of static and dynamic pressure-diameter (P-D) loops. The dynamic trace (green) was created by plotting pressure against diameter for the heartbeat in A and is superimposed on a P-D curve (black) created by a bulbar inflation from a syringe, post mortem. Arrows indicate the clockwise or anticlockwise cycling of the loop. (Diameter ratio is the diameter divided by the initial diameter.)\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 2.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F2.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 2.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F2.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F2.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 2.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F2.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079123\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 2.\u003C\/span\u003E \n \u003Cp id=\u0022p-16\u0022 class=\u0022first-child\u0022\u003E(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna.\n(B) Comparison of static and dynamic pressure-diameter (P-D) loops. The\ndynamic trace (green) was created by plotting pressure against diameter for\nthe heartbeat in A and is superimposed on a P-D curve (black) created by a\nbulbar inflation from a syringe, \u003Cem\u003Epost mortem\u003C\/em\u003E. Arrows indicate the\nclockwise or anticlockwise cycling of the loop. (Diameter ratio is the\ndiameter divided by the initial diameter.)\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-17\u0022\u003EThe difference between the areas under the inflation and deflation curves\nis the amount of energy lost as heat. When this loss is normalized to the area\nunder the inflation curve, the resulting percentage is known as hysteresis.\nThere was significant hysteresis in both loops, indicative of a viscous\nelement in the bulbar wall. In the dynamic loop, the larger hysteresis was due\nto the increased rate at which the bulbus was inflated. The faster the changes\nin the dimensions of a viscous element, the stiffer it becomes, and more\nenergy is lost executing the changes.\u003C\/p\u003E\n \u003Cp id=\u0022p-18\u0022\u003EDuring the initial rise of the r-curve, the inflation and deflation curves\ncrossed over, indicating energy added. The bulbus lacks cardiac muscle and\ncannot contract beat-to-beat; therefore, the positive work loop was due to the\nchanging length of the bulbus. The change in the length of the bulbus could be\nclearly seen at the end of the deflation\n(\u003Ca id=\u0022xref-fig-2-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig. 2B\u003C\/a\u003E). While pressure\ncontinued to drop, the diameter of the bulbus increased, indicating wider,\nupstream segments entering the field of view of the video camera.\u003C\/p\u003E\n \u003Cp id=\u0022p-19\u0022\u003EThe dynamic P-D loop in \u003Ca id=\u0022xref-fig-2-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003EFig.\n2B\u003C\/a\u003E demonstrates bulbar behaviour over the pressure range of 4-9.5\nkPa. However, by looking at beats covering the pressure range of 2.5-21.5 kPa,\nthe features of the static bulbar inflation curve\n(\u003Ca id=\u0022xref-fig-3-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig. 3A\u003C\/a\u003E) were recreated: the\ninitial steep rise, the plateau and the final steep rise at large inflations\nand high pressures (\u003Ca id=\u0022xref-ref-4-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBraun et al.,\n2003\u003C\/a\u003E). At the low end of the pressure range, the bulbus was\noperating on the steep part of the inflation curve and small changes in volume\nresulted in large, rapid changes in pressure\n(\u003Ca id=\u0022xref-fig-3-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig. 3B\u003C\/a\u003E). A small,\nlow-pressure heart beat generated a very steep P-D loop. For a heart beat\ncovering the pressure range 11.3-12.6 kPa, the P-D loop showed that the bulbus\nwas inflating entirely on the plateau (\u003Ca id=\u0022xref-fig-3-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig.\n3C\u003C\/a\u003E); the loop was horizontal, with very little vertical component.\nThe P-D loop from a heart beat over the range of 15.3-22.6 kPa showed that,\nwhile the bulbus operated on the plateau for much of the beat, at very high\nblood pressures bulbus stiffness rapidly increased\n(\u003Ca id=\u0022xref-fig-3-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003EFig. 3D\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-20\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F3\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F3.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Comparison of dynamic and static inflations over a wide pressure range. (A) Pressure-volume (P-V) loop from static inflation of a yellowfin tuna bulbus arteriosus. (B) A dynamic pressure-diameter (P-D) loop for the pressure range 4-8 kPa. (C) A dynamic P-D loop for the pressure range 10.6-12.6 kPa. (D) A dynamic P-D loop for the pressure range 16-22 kPa. Arrows link the pressure ranges in B, C and D to the static loop in A.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Comparison of dynamic and static inflations over a wide pressure range. (A) Pressure-volume (P-V) loop from static inflation of a yellowfin tuna bulbus arteriosus. (B) A dynamic pressure-diameter (P-D) loop for the pressure range 4-8 kPa. (C) A dynamic P-D loop for the pressure range 10.6-12.6 kPa. (D) A dynamic P-D loop for the pressure range 16-22 kPa. Arrows link the pressure ranges in B, C and D to the static loop in A.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 3.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F3.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 3.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F3.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F3.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 3.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F3.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079125\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 3.\u003C\/span\u003E \n \u003Cp id=\u0022p-21\u0022 class=\u0022first-child\u0022\u003EComparison of dynamic and static inflations over a wide pressure range. (A)\nPressure-volume (P-V) loop from static inflation of a yellowfin tuna bulbus\narteriosus. (B) A dynamic pressure-diameter (P-D) loop for the pressure range\n4-8 kPa. (C) A dynamic P-D loop for the pressure range 10.6-12.6 kPa. (D) A\ndynamic P-D loop for the pressure range 16-22 kPa. Arrows link the pressure\nranges in B, C and D to the static loop in A.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-22\u0022\u003EIn \u003Ca id=\u0022xref-fig-4-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4A\u003C\/a\u003E, following a\nprolonged cardiac interval (marked with an asterisk), the smallest increase in\ndiameter resulted in the generation of the largest pressure pulse. As peak\npressure increased, subsequent pressure pulses became smaller while diameter\nchanges increased. The first fluid injection after the long cardiac interval\nhad a larger impact on the pressure than those that followed. The highlighted\nbeat (marked with an asterisk) is equivalent to the sharp initial rise of the\nstatic inflation tests.\u003C\/p\u003E\n \u003Cp id=\u0022p-23\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F4\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F4.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Recordings of bulbar blood pressure and diameter from yellowfin tuna. (A) Following a long cardiac interval, the smallest stroke volume (*) generated the largest pulse pressure. (B) At mean systolic pressure, large changes in diameter result in small changes in pressure (arrows). See text for explanation of diamond. (C) At very high pressures, small changes in diameter result in large fluctuations in pressure (triangles).\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;Recordings of bulbar blood pressure and diameter from yellowfin tuna. (A) Following a long cardiac interval, the smallest stroke volume (*) generated the largest pulse pressure. (B) At mean systolic pressure, large changes in diameter result in small changes in pressure (arrows). See text for explanation of diamond. (C) At very high pressures, small changes in diameter result in large fluctuations in pressure (triangles).\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 4.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F4.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 4.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F4.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F4.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 4.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F4.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079127\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 4.\u003C\/span\u003E \n \u003Cp id=\u0022p-24\u0022 class=\u0022first-child\u0022\u003ERecordings of bulbar blood pressure and diameter from yellowfin tuna. (A)\nFollowing a long cardiac interval, the smallest stroke volume (\u003Csup\u003E*\u003C\/sup\u003E)\ngenerated the largest pulse pressure. (B) At mean systolic pressure, large\nchanges in diameter result in small changes in pressure (arrows). See text for\nexplanation of diamond. (C) At very high pressures, small changes in diameter\nresult in large fluctuations in pressure (triangles).\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-25\u0022\u003EImmediately after Saffan injection, the tuna hearts often deviated from\nnormal beating patterns by speeding up and\/or increasing pressure. In a fish\nrecently injected with Saffan (\u003Ca id=\u0022xref-fig-4-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig.\n4B\u003C\/a\u003E), the lowest diastolic pressure was 6.7 kPa, while the highest\npressure was 20.6 kPa. During a period of declining pressure, there was an\noccasional small pressure `blip\u201d (arrows in\n\u003Ca id=\u0022xref-fig-4-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4B\u003C\/a\u003E). The small increases\nin pressure (0.13-0.67 kPa) were associated with large changes in the diameter\nof the bulbus. These diameter changes were frequently as large as those\nassociated with pressure changes that were \u226520 times larger (diamond in\n\u003Ca id=\u0022xref-fig-4-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4B\u003C\/a\u003E). In the high-pressure\nrange (13.3-16 kPa), large volume changes (as evidenced by large changes in\nbulbar diameter) result in relatively small changes in pressure, indicating\nthat the bulbus was on the plateau stage of static inflations.\u003C\/p\u003E\n \u003Cp id=\u0022p-26\u0022\u003EAt pressures greater than 17.3 kPa, however, small volume changes resulted\nin large changes in pressure. In \u003Ca id=\u0022xref-fig-4-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig.\n4C\u003C\/a\u003E, the highlighted beats (triangles) had peak systolic pressures\nof 17.3 kPa, 22.7 kPa and 22.2 kPa. However, the resultant systolic diameters\nonly varied slightly (1.077-1.095 cm) and the systolic-diastolic diameter\nchanges were 0.18-0.23 cm. The insensitivity of the bulbar pressure to volume\ninjections disappeared at very high pressures due to a rapid increase in the\nstiffness of the bulbar wall.\u003C\/p\u003E\n \u003Cp id=\u0022p-27\u0022\u003EDynamic P-D loops (Figs \u003Ca id=\u0022xref-fig-2-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F2\u0022\u003E2\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-3-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003E3\u003C\/a\u003E) had the same features as the\nstatic P-V loops, and bulbar diameter seemed to be an accurate indication of\nbulbar volume. The validity of this assumption was checked by static\ninflations. Static r-shaped P-V loops were generated using the \u003Cem\u003Ein\nsitu\u003C\/em\u003E VDA preparations after dynamic experiments\n(\u003Ca id=\u0022xref-fig-5-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5\u003C\/a\u003E). The relationship\nbetween diameter and volume was linear for examples from both the anterior\n(\u003Ca id=\u0022xref-fig-5-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5C\u003C\/a\u003E) and posterior\n(\u003Ca id=\u0022xref-fig-5-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5D\u003C\/a\u003E) portions of the\nbulbus.\u003C\/p\u003E\n \u003Cp id=\u0022p-28\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F5\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F5.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022(A) Pressure-volume (P-V) loops from static, in situ inflations of bulbi from yellowfin tuna. Anterior and posterior refer to where on the bulbus the video dimensional analysis (VDA) window was centred. (B) Pressure-diameter strain loop for the same bulbi as in A. The diameter strain was calculated using diameter data from the VDA. (C) Diameter plotted against volume for the bulbus measured at the anterior end. A linear regression was run on this plot and the solution is shown. (D) Diameter plotted against volume for the bulbus measured at the posterior end. A linear regression was run on this plot and the solution is shown.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;(A) Pressure-volume (P-V) loops from static, in situ inflations of bulbi from yellowfin tuna. Anterior and posterior refer to where on the bulbus the video dimensional analysis (VDA) window was centred. (B) Pressure-diameter strain loop for the same bulbi as in A. The diameter strain was calculated using diameter data from the VDA. (C) Diameter plotted against volume for the bulbus measured at the anterior end. A linear regression was run on this plot and the solution is shown. (D) Diameter plotted against volume for the bulbus measured at the posterior end. A linear regression was run on this plot and the solution is shown.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 5.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F5.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 5.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F5.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F5.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 5.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F5.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079129\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 5.\u003C\/span\u003E \n \u003Cp id=\u0022p-29\u0022 class=\u0022first-child\u0022\u003E(A) Pressure-volume (P-V) loops from static, \u003Cem\u003Ein situ\u003C\/em\u003E inflations of\nbulbi from yellowfin tuna. Anterior and posterior refer to where on the bulbus\nthe video dimensional analysis (VDA) window was centred. (B) Pressure-diameter\nstrain loop for the same bulbi as in A. The diameter strain was calculated\nusing diameter data from the VDA. (C) Diameter plotted against volume for the\nbulbus measured at the anterior end. A linear regression was run on this plot\nand the solution is shown. (D) Diameter plotted against volume for the bulbus\nmeasured at the posterior end. A linear regression was run on this plot and\nthe solution is shown.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-30\u0022\u003E\u003Ca id=\u0022xref-fig-6-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003EFig. 6\u003C\/a\u003E is an example of a\ntypical beating pattern for an anaesthetized yellowfin tuna. The diameter and\npressure were measured at a point near the middle of the bulbus. At a heart\nrate of 1 Hz, pulse pressure was approximately 6 kPa with a peak systolic\npressure of 10 kPa. Diameter changes were about 0.1 cm, from 0.7 cm to 0.8 cm.\n\u003Ca id=\u0022xref-fig-6-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003EFig. 6B\u003C\/a\u003E illustrates how these\ndiameter changes translated into volume within the bulbus. The 0.1 cm-diameter\nchange resulted in bulbar volume varying from 0.2 ml to 0.8 ml.\u003C\/p\u003E\n \u003Cp id=\u0022p-31\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F6\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F6.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna during normal beating. (B) The volume changes within the bulbus during the beating in A.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna during normal beating. (B) The volume changes within the bulbus during the beating in A.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 6.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F6.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 6.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F6.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F6.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 6.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F6.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079131\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 6.\u003C\/span\u003E \n \u003Cp id=\u0022p-32\u0022 class=\u0022first-child\u0022\u003E(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna\nduring normal beating. (B) The volume changes within the bulbus during the\nbeating in A.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-33\u0022\u003EBulbar volume fell when blood pressure and heart rate decreased. In\n\u003Ca id=\u0022xref-fig-7-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig. 7A,B\u003C\/a\u003E, the heart was\nbeating normally during the first 12 s, after which it began to slow from a\nrate of 1.2 Hz to 0.8 Hz. Bulbus diameter and internal volume began to fall,\nand, between 20 s and 25 s, the heart appeared to miss several beats,\nresulting in long diastolic periods. During these periods, bulbar volume fell\nclose to zero. However, even at these low internal volumes, the pressure\nremained at 2.7 kPa (\u003Ca id=\u0022xref-fig-7-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig.\n7A,B\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-34\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F7\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F7.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna during a marked fall in pressure and heart rate. (B) Volume changes within the bulbus from A. (C) Pressure and diameter from a tuna after Saffan injection. (D) Volume changes within the bulbus from C.\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna during a marked fall in pressure and heart rate. (B) Volume changes within the bulbus from A. (C) Pressure and diameter from a tuna after Saffan injection. (D) Volume changes within the bulbus from C.\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 7.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F7.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 7.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F7.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F7.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 7.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F7.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079133\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 7.\u003C\/span\u003E \n \u003Cp id=\u0022p-35\u0022 class=\u0022first-child\u0022\u003E(A) Recordings of bulbar blood pressure and diameter from a yellowfin tuna\nduring a marked fall in pressure and heart rate. (B) Volume changes within the\nbulbus from A. (C) Pressure and diameter from a tuna after Saffan injection.\n(D) Volume changes within the bulbus from C.\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-36\u0022\u003E\u003Ca id=\u0022xref-fig-7-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig. 7C\u003C\/a\u003E shows a VDA\nrecording of the ventricular end of the bulbus from a fish shortly after an\ninter-arterial injection of Saffan. The heart was beating extremely fast (4\nHz) and pulse pressure was approximately 2 kPa (10.6-12.6 kPa). Despite the\nsmall pulse pressure, the changes in diameter (0.08 cm) were nearly as large\nas in Figs \u003Ca id=\u0022xref-fig-6-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003E6B\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-7-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003E7B\u003C\/a\u003E. This suggests that the\nbulbus was on the plateau phase of the r-shaped curve; large changes in volume\ngenerated small changes in pressure. Indeed, the volume changes (0.6-1 ml)\nseen in \u003Ca id=\u0022xref-fig-7-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig. 7D\u003C\/a\u003E were similar to\nthose in \u003Ca id=\u0022xref-fig-6-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003EFig. 6\u003C\/a\u003E.\u003C\/p\u003E\n \u003C\/div\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-6\u0022\u003E\n \u003Ch2\u003EDiscussion\u003C\/h2\u003E\n \u003Cp id=\u0022p-37\u0022\u003EIn simple geometrical figures like cones or spheres, the relationship\nbetween diameter and volume is not linear. Bulbus geometry, however, is not\nsimple and the analysis was further complicated because the bulbus lengthened\nas it inflated (\u003Ca id=\u0022xref-fig-1-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFig. 1\u003C\/a\u003E). Since\nthe VDA windows were fixed, the point that was followed at the start of the\ninflation was not the point being followed at the end. The result of this was\na consistent underestimation of the actual diameter changes as narrower,\nmore-distal portions of the bulbus were being `pushed\u0027 into the field of view.\nThe unexpected linear relationship between diameter and volume in the bulbus\nis a coincidence between the interactions of the linear and radial expansions\nand how they were interpreted by the VDA. This was shown by modelling volume\nand diameter changes in cones undergoing hypothetical inflations\n(\u003Ca id=\u0022xref-ref-3-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-3\u0022\u003EBraun, 2001\u003C\/a\u003E). Cones modelled\nwith longitudinal and circumferential strains equivalent to those that the\nbulbus experienced also showed a linear relationship between diameter and\nvolume.\u003C\/p\u003E\n \u003Cp id=\u0022p-38\u0022\u003EQualitatively, the linear relationship between diameter and volume allowed\nthe inference that a change in diameter was due to an equivalent change in\nvolume: if one heart beat resulted in a bulbus diameter change twice as large\nas another, then twice as much fluid entered the bulbus during that beat.\nQuantitatively, the fact that a linear regression closely described the\ninteraction between diameter and volume\n(\u003Ca id=\u0022xref-fig-5-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F5\u0022\u003EFig. 5\u003C\/a\u003E) allowed an analysis of\nthe volume into and out of the bulbus with each beat.\u003C\/p\u003E\n \u003Cp id=\u0022p-39\u0022\u003EThe features of the static bulbar inflation curve\n(\u003Ca id=\u0022xref-ref-4-4\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBraun et al., 2003\u003C\/a\u003E) occur\n\u003Cem\u003Ein vivo\u003C\/em\u003E. Blood initially entering the bulbus caused a large jump in\npressure, followed by a stage in which large volume changes result in small\npressure differences. At very high pressures, bulbar stiffness rapidly rose,\nand the ability to expand further was limited.\u003C\/p\u003E\n \u003Cp id=\u0022p-40\u0022\u003EBoth the sharp initial rise in pressure and the compliant plateau phase are\nimportant in the bulbus\u0027 function as a pressure reservoir. Due to the Law of\nLaplace (tension = pressure \u00d7 radius), the relatively small internal\nlumen of the bulbus results in a negligible tension in the bulbar wall at low\npressures (\u003Ca id=\u0022xref-ref-4-5\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBraun et al., 2003\u003C\/a\u003E).\nThis small internal radius necessitates a large pressure in order for\nexpansion to occur and results in the large initial jump in the bulbar P-V\nloop (\u003Ca id=\u0022xref-fig-8-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8A\u003C\/a\u003E). The larger\nlumen radius of an artery allows much larger changes in volume at low\npressures due to the larger tension generated\n(\u003Ca id=\u0022xref-fig-8-2\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8A\u003C\/a\u003E). For the example in\n\u003Ca id=\u0022xref-fig-8-3\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8B\u003C\/a\u003E, the tension initially\ncreated in the artery is over four times larger than in the bulbus. Arteries\ngenerally expand 40-50% when pressurized to physiological ranges\n(\u003Ca id=\u0022xref-ref-16-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-16\u0022\u003EMcDonald, 1974\u003C\/a\u003E). In the\nyellowfin tuna bulbus, going from zero to physiological pressure requires a\nstrain of around 10%. The bulbus can reach the same pressure as an artery at a\nfraction of the volume (\u003Ca id=\u0022xref-fig-8-4\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig.\n8A\u003C\/a\u003E, broken arrow), which allows the bulbus to become `primed\u0027 to a\nhigh pressure with a single heartbeat, regardless of cardiac output.\u003C\/p\u003E\n \u003Cp id=\u0022p-41\u0022\u003E\n \n \u003C\/p\u003E\u003Cdiv id=\u0022F8\u0022 class=\u0022fig pos-float odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F8.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022(A) Comparison between pressure-volume (P-V) loops from a yellowfin tuna bulbus arteriosus and ventral aorta. The broken arrows indicate the normalized volume required to reach the indicated pressure. The solid arrows indicate the volume change (\u0026#x394;V) experienced by the bulbus arteriosus and ventral aorta over a physiological pressure range. The thick vertical lines indicate the bulbar volume changes, and the thin vertical lines indicate the ventral aortic changes. Volume was normalized to maximal internal volume. (B) Dimensional changes that a bulbus and a ventral aorta of the same external diameter would undergo from zero to diastolic and then to systolic pressure. Zero to diastolic pressure. At zero pressure, the bulbus\u0027 lumen is smaller than the artery\u0027s lumen, resulting in a much lower tension during inflation. The low tension in the bulbar wall results in a requirement for a large pressure to allow expansion. As shown in A, the small strain change in the bulbus generates a large pressure for a small volume. Diastolic to systolic pressure. During inflation from diastole to systole, the bulbus undergoes a large strain (35%) due to the large volume changes seen in A at systolic pressure. The artery undergoes a strain of 5%, due to the low compliance seen in A at systolic pressure. D, external diameter; d, lumen diameter. Values of strain for the bulbus were calculated using video dimensional analysis (VDA). Values of strain for the proximal aorta came from McDonald (1974).\u0022 class=\u0022highwire-fragment fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1050261967\u0022 data-figure-caption=\u0022\u0026lt;div class=\u0026quot;highwire-markup\u0026quot;\u0026gt;(A) Comparison between pressure-volume (P-V) loops from a yellowfin tuna bulbus arteriosus and ventral aorta. The broken arrows indicate the normalized volume required to reach the indicated pressure. The solid arrows indicate the volume change (\u0026#x394;V) experienced by the bulbus arteriosus and ventral aorta over a physiological pressure range. The thick vertical lines indicate the bulbar volume changes, and the thin vertical lines indicate the ventral aortic changes. Volume was normalized to maximal internal volume. (B) Dimensional changes that a bulbus and a ventral aorta of the same external diameter would undergo from zero to diastolic and then to systolic pressure. Zero to diastolic pressure. At zero pressure, the bulbus\u0027 lumen is smaller than the artery\u0027s lumen, resulting in a much lower tension during inflation. The low tension in the bulbar wall results in a requirement for a large pressure to allow expansion. As shown in A, the small strain change in the bulbus generates a large pressure for a small volume. Diastolic to systolic pressure. During inflation from diastole to systole, the bulbus undergoes a large strain (35%) due to the large volume changes seen in A at systolic pressure. The artery undergoes a strain of 5%, due to the low compliance seen in A at systolic pressure. D, external diameter; d, lumen diameter. Values of strain for the bulbus were calculated using video dimensional analysis (VDA). Values of strain for the proximal aorta came from McDonald (1974).\u0026lt;\/div\u0026gt;\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cspan class=\u0022hw-responsive-img\u0022\u003E\u003Cimg class=\u0022highwire-fragment fragment-image lazyload\u0022 alt=\u0022Fig. 8.\u0022 src=\u0022data:image\/gif;base64,R0lGODlhAQABAIAAAAAAAP\/\/\/yH5BAEAAAAALAAAAAABAAEAAAIBRAA7\u0022 data-src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F8.medium.gif\u0022\/\u003E\u003Cnoscript\u003E\u003Cimg class=\u0022highwire-fragment fragment-image\u0022 alt=\u0022Fig. 8.\u0022 src=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F8.medium.gif\u0022\/\u003E\u003C\/noscript\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u0022download-fig first\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F8.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Fig. 8.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022new-tab\u0022\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/jexbio\/206\/19\/3327\/F8.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u0022download-ppt last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/1079135\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFig. 8.\u003C\/span\u003E \n \u003Cp id=\u0022p-42\u0022 class=\u0022first-child\u0022\u003E(A) Comparison between pressure-volume (P-V) loops from a yellowfin tuna\nbulbus arteriosus and ventral aorta. The broken arrows indicate the normalized\nvolume required to reach the indicated pressure. The solid arrows indicate the\nvolume change (\u0394\u003Cem\u003EV\u003C\/em\u003E) experienced by the bulbus arteriosus and\nventral aorta over a physiological pressure range. The thick vertical lines\nindicate the bulbar volume changes, and the thin vertical lines indicate the\nventral aortic changes. Volume was normalized to maximal internal volume. (B)\nDimensional changes that a bulbus and a ventral aorta of the same external\ndiameter would undergo from zero to diastolic and then to systolic pressure.\n\u003Cem\u003EZero to diastolic pressure.\u003C\/em\u003E At zero pressure, the bulbus\u0027 lumen is\nsmaller than the artery\u0027s lumen, resulting in a much lower tension during\ninflation. The low tension in the bulbar wall results in a requirement for a\nlarge pressure to allow expansion. As shown in A, the small strain change in\nthe bulbus generates a large pressure for a small volume. \u003Cem\u003EDiastolic to\nsystolic pressure\u003C\/em\u003E. During inflation from diastole to systole, the bulbus\nundergoes a large strain (35%) due to the large volume changes seen in A at\nsystolic pressure. The artery undergoes a strain of 5%, due to the low\ncompliance seen in A at systolic pressure. \u003Cem\u003ED\u003C\/em\u003E, external diameter;\n\u003Cem\u003Ed\u003C\/em\u003E, lumen diameter. Values of strain for the bulbus were calculated\nusing video dimensional analysis (VDA). Values of strain for the proximal\naorta came from McDonald\n(\u003Ca id=\u0022xref-ref-16-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-16\u0022\u003E1974\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003Cp id=\u0022p-43\u0022\u003EWhen stroke volume is high, the compliance of the bulbus allows it to\nexpand and `absorb\u0027 excess fluid while preserving a relatively constant\npressure head. Even when stroke volume is low, the bulbus will maintain blood\nflow through the gills at a high pressure. Following a long diastolic period,\nthe first heartbeat will have a larger effect on pressure than any following\nbeats (\u003Ca id=\u0022xref-fig-4-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003EFig. 4A\u003C\/a\u003E). The benefit of\nthe bulbar design is that it allows the bulbus to behave similarly under both\nhigh and low cardiac outputs.\u003C\/p\u003E\n \u003Cp id=\u0022p-44\u0022\u003EIn rainbow trout (\u003Cem\u003EOncorhynchus mykiss\u003C\/em\u003E), the bulbus is most\ncompliant near the systolic pressure (\u003Ca id=\u0022xref-ref-7-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-7\u0022\u003EClark\nand Rodnick, 1999\u003C\/a\u003E), and the same phenomenon occurs in yellowfin\ntuna. During systole, increasingly large changes in volume result in\nrelatively small pressure increases. Once systolic pressure has been reached,\nthe compliant plateau of the bulbus allows it to effectively `store\u0027 pressure,\ndespite large increases in volume. During diastole, the plateau allows the\nbulbus to maintain a high pressure while internal volume is decreasing. In\nfact, the bulbus can lose most of its volume, and pressure only falls by a\nsmall amount (\u003Ca id=\u0022xref-fig-8-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8A\u003C\/a\u003E, solid\narrows). In this manner, the bulbus extends the proportion of the cardiac\ncycle during which blood flows into the gills\n(\u003Ca id=\u0022xref-ref-19-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-19\u0022\u003ERandall, 1968\u003C\/a\u003E;\n\u003Ca id=\u0022xref-ref-22-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-22\u0022\u003EStevens et al., 1972\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-45\u0022\u003EOver a physiological pressure range of 4 kPa, the bulbus can hold and\nreturn 90% of its volume (\u003Ca id=\u0022xref-fig-8-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig.\n8A\u003C\/a\u003E, thick, solid arrows), compared with only 15% in an artery.\nBulbar volume changes of 0.2-0.8 ml yield circumferential strain changes of\n30-40% (\u003Ca id=\u0022xref-fig-8-7\u0022 class=\u0022xref-fig\u0022 href=\u0022#F8\u0022\u003EFig. 8B\u003C\/a\u003E). This\nbehaviour is in stark contrast to arteries, which typically experience\ncircumferential strains of 2-7% during an inflation cycle\n(\u003Ca id=\u0022xref-ref-16-3\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-16\u0022\u003EMcDonald, 1974\u003C\/a\u003E). These large\ndifferences between the behaviour of arteries and bulbi illustrate two\ndifferent means to the same end. Both bulbi and arteries are designed to\nincrease the capacitance in the circulatory system in order to depulsate and\nattenuate flows and pressures. Capacitance in arteries is achieved through\nlength. Even a relatively inextensible tube can provide significant\ncapacitance if it is of sufficient length. Teleosts lack the luxury of a long\narterial tree separating the heart from the gills. Instead, capacitance is\nincreased by the bulbus and its r-shaped inflation. The tremendous compliance\nof the bulbus on the plateau of its P-V loop results in a large volume change\n(\u0394\u003Cem\u003EV\u003C\/em\u003E) over the physiological pressure range and allows a\nrelatively short bulbus to greatly increase the capacitance of the teleost\narterial system. Furthermore, an artery needs to be almost completely filled\nin order to reach a high pressure, at which point a rapid increase in\nstiffness occurs. Working against the very rigid walls of an artery-like\nbulbus would increase the work of the heart. During diastole, a small amount\nof fluid loss in an artery results in a rapid fall in pressure. The bulbus\nordinarily experiences large volume changes; in an artery-like bulbus, much of\nthe diastolic period would occur at low pressure, reducing the flow of blood\nthough the gills.\u003C\/p\u003E\n \u003Cp id=\u0022p-46\u0022\u003EThe bulbus is capable of both expanding to store cardiac output and\nrecoiling elastically to return the stored fluid to the circulation. When\ncontracted, bulbar volume is smaller than a single stroke volume. However, the\nbulbus is capable of holding a very large blood volume: 200-300% of stroke\nvolume (\u003Ca id=\u0022xref-ref-5-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-5\u0022\u003EBushnell et al., 1992\u003C\/a\u003E).\nDuring diastole, it is important to have some way of maintaining blood flow\nthrough the gills. Observation of the bulbus\u0027 \u003Cem\u003Ein vivo\u003C\/em\u003E functioning\nshows that it maintains a reservoir and never completely empties during\ndiastole (Figs \u003Ca id=\u0022xref-fig-6-5\u0022 class=\u0022xref-fig\u0022 href=\u0022#F6\u0022\u003E6\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-7-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003E7\u003C\/a\u003E). Following a bradycardia,\nthe bulbus `pumps\u0027 up until the reserves are replenished\n(\u003Ca id=\u0022xref-fig-7-7\u0022 class=\u0022xref-fig\u0022 href=\u0022#F7\u0022\u003EFig. 7A,B\u003C\/a\u003E). The bulbar\nreservoir allows positive flow to occur during long diastolic periods. In ling\ncod (\u003Cem\u003EOphiodon elongatus\u003C\/em\u003E), blood flow in the ventral aorta due to the\nelastic rebound of the bulbus arteriosus represents about 29% of total cardiac\noutput (\u003Ca id=\u0022xref-ref-19-2\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-19\u0022\u003ERandall, 1968\u003C\/a\u003E).\u003C\/p\u003E\n \u003Cp id=\u0022p-47\u0022\u003EThe central location of the bulbus has benefits to the teleost circulatory\nsystem. A model study performed by Campbell et al.\n(\u003Ca id=\u0022xref-ref-6-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-6\u0022\u003E1981\u003C\/a\u003E) showed that a large\ncompliance located far from the heart is equally good at raising diastolic\npressure as one located proximally, but only a compliance located directly\noutside the heart effectively decreases peak systolic pressure. An elevated\ndiastolic pressure ensures continuing flow through peripheral vascular beds\nduring diastole, while decreasing the peak systolic pressure translates into\nlarge cardiac energy savings by lowering the tension-time integral during\ncardiac contraction. The majority of the heart\u0027s work is involved in\ngenerating tension rather than in ejecting blood from the heart.\n(\u003Ca id=\u0022xref-ref-11-1\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-11\u0022\u003EJones, 1991\u003C\/a\u003E). Therefore, the\nposition of the bulbus in the teleost circulation, just distal to the heart,\nmakes it of great importance for increasing the overall efficiency of the\npiscine cardiovascular system.\u003C\/p\u003E\n \u003Cp id=\u0022p-48\u0022\u003EAt large volumes, the bulbus increases in stiffness\n(\u003Ca id=\u0022xref-ref-4-6\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003EBraun et al., 2003\u003C\/a\u003E). As in\narteries, this feature may serve a similar strain-limitation function in the\nbulbus. However, the pressures at which this rise in stiffness occurs are\nextreme. In yellowfin tuna, pressures in excess of 20 kPa were required for\nthe final increase in stiffness to occur. Normal static inflations were never\ntaken to this level for two reasons: (1) the preparations would begin to leak\nand (2) the very high pressures are far above the normal \u003Cem\u003Ein vivo\u003C\/em\u003E\npressure range (\u003Ca id=\u0022xref-ref-14-4\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-14\u0022\u003EJones et al.,\n1993\u003C\/a\u003E). Clues suggesting that the bulbus did indeed possess a final\nrise in stiffness came from several sources. Braun et al.\n(\u003Ca id=\u0022xref-ref-4-7\u0022 class=\u0022xref-bibr\u0022 href=\u0022#ref-4\u0022\u003E2003\u003C\/a\u003E), after dissecting out\nthe bulbar media, demonstrated bulbar inflations with a rapid rise in\nstiffness at large volumes. In the present study, the analysis of very high\n(\u0026gt;20 kPa) blood pressure traces showed that, in contrast to what ordinarily\noccurs on the plateau, large jumps in pressure were occurring for very small\nchanges in dimension (Figs \u003Ca id=\u0022xref-fig-3-6\u0022 class=\u0022xref-fig\u0022 href=\u0022#F3\u0022\u003E3\u003C\/a\u003E,\n\u003Ca id=\u0022xref-fig-4-7\u0022 class=\u0022xref-fig\u0022 href=\u0022#F4\u0022\u003E4C\u003C\/a\u003E), indicating an increased\nstiffness. In reality, however, the bulbar location within the pericardium\nmeans that the third phase may never be attained in an intact animal. An\nextremely full and swollen bulbus could interfere with the functioning of the\natrium, reducing cardiac output and causing the bulbus to empty and shrink,\nwhile the very rigid pericardium found in these fish would also limit the size\nto which the bulbus could expand.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cdiv class=\u0022section ack\u0022 id=\u0022ack-1\u0022\u003E\u003Ch2\u003EACKNOWLEDGEMENTS\u003C\/h2\u003E\n \u003Cp id=\u0022p-49\u0022\u003EThis research was supported by equipment and operating grants to D.R.J. and\nJ.M.G. from NSERCC. R.W.B.\u0027s participation was funded through Cooperative\nAgreements NA37RJ0199 and NA67RJ0154 from the National Oceanic and Atmospheric\nAdministration with the Joint Institute for Marine and Atmospheric Research,\nUniversity of Hawaii. The views expressed herein are those of the authors and\ndo not necessarily reflect the views of NOAA or any of its subagencies.\u003C\/p\u003E\n \u003C\/div\u003E\u003Cul class=\u0022copyright-statement\u0022\u003E\u003Cli class=\u0022fn\u0022 id=\u0022copyright-statement-1\u0022\u003E\u00a9 The Company of Biologists Limited\n2003\u003C\/li\u003E\u003C\/ul\u003E\u003Cdiv class=\u0022section ref-list\u0022 id=\u0022ref-list-1\u0022\u003E\u003Ch2\u003EReferences\u003C\/h2\u003E\u003Col class=\u0022cit-list ref-use-labels\u0022\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-1-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-1\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.1\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBenjamin, M., Norman, D., Santer, R. M. and Scarborough, D.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1983\u003C\/span\u003E). Histological, histochemical and ultrastructural studies\non the bulbus arteriosus of the stickle-backs, \u003Cem\u003EGasterosteus aculeatus\u003C\/em\u003E\nand \u003Cem\u003EPungitius pungitius\u003C\/em\u003E (Pisces: Teleostei). \u003Cspan class=\u0022cit-source\u0022\u003EJ. Zool.\nLond\u003C\/span\u003E. \u003Cspan class=\u0022cit-vol\u0022\u003E200\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E325\u003C\/span\u003E\n-346.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BZool.%250ALond%26rft.volume%253D200%26rft.spage%253D325%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-2-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-2\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.2\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBenjamin, M., Norman, D., Scarborough, D. and Santer, R. M.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1984\u003C\/span\u003E). Carbohydrate-containing endothelial cells lining the\nbulbus arteriosus of teleosts and conus arteriosus of elasmobranches (Pisces).\n\u003Cspan class=\u0022cit-source\u0022\u003EJ. Zool. Lond\u003C\/span\u003E. \u003Cspan class=\u0022cit-vol\u0022\u003E202\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E383\u003C\/span\u003E\n-392.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BZool.%2BLond%26rft.volume%253D202%26rft.spage%253D383%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-3-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-3\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.3\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBraun, M. H.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E2001\u003C\/span\u003E). The bulbus arteriosus of\ntuna; form and function. \u003Cspan class=\u0022cit-source\u0022\u003EMSc. Thesis\u003C\/span\u003E. University of British\nColumbia: Vancouver, BC, Canada.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-4-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-4\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.4\u0022 data-doi=\u002210.1242\/jeb.00575\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBraun, M. H., Brill, R. W., Gosline, J. M. and Jones, D. R.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E2003\u003C\/span\u003E). Form and function of the bulbus arteriosus in yellowfin\ntuna (\u003Cem\u003EThunnus albacares\u003C\/em\u003E), bigeye tuna (\u003Cem\u003EThunnus obesus\u003C\/em\u003E) and\nblue marlin (\u003Cem\u003EMakaira nigricans\u003C\/em\u003E): static properties. \u003Cspan class=\u0022cit-source\u0022\u003EJ.\nExp. Biol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E206\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E3311\u003C\/span\u003E\n-3326.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DBraun%26rft.auinit1%253DM.%2BH.%26rft.volume%253D206%26rft.issue%253D19%26rft.spage%253D3311%26rft.epage%253D3326%26rft.atitle%253DForm%2Band%2Bfunction%2Bof%2Bthe%2Bbulbus%2Barteriosus%2Bin%2Byellowfin%2Btuna%2B%2528Thunnus%2Balbacares%2529%252C%2Bbigeye%2Btuna%2B%2528Thunnus%2Bobesus%2529%2Band%2Bblue%2Bmarlin%2B%2528Makaira%2Bnigricans%2529%253A%2Bstatic%2Bproperties%26rft_id%253Dinfo%253Adoi%252F10.1242%252Fjeb.00575%26rft_id%253Dinfo%253Apmid%252F12939364%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjExOiIyMDYvMTkvMzMxMSI7czo0OiJhdG9tIjtzOjI0OiIvamV4YmlvLzIwNi8xOS8zMzI3LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-5-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-5\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.5\u0022 data-doi=\u002210.1016\/S1546-5098(08)60332-5\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EBushnell, P. G., Jones, D. R. and Farrell, A. P.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1992\u003C\/span\u003E). The arterial system. In \u003Cspan class=\u0022cit-source\u0022\u003EFish\nPhysiology\u003C\/span\u003E, vol. \u003Cspan class=\u0022cit-vol\u0022\u003E12A\u003C\/span\u003E (ed. W. S. Hoar, D.\nJ. Randall and A. P. Farrell), pp. \u003Cspan class=\u0022cit-fpage\u0022\u003E89\u003C\/span\u003E-120. New York:\nAcademic Press.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DFish%250APhysiology%26rft.volume%253D12%26rft.spage%253D89%26rft_id%253Dinfo%253Adoi%252F10.1016%252FS1546-5098%252808%252960332-5%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1016\/S1546-5098(08)60332-5\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-6-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-6\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.6\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ECampbell, K. B., Rhode, E. A., Cox, R. H., Hunter, W. C. and\nNoordergraaf, A.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1981\u003C\/span\u003E). Functional consequences of expanded\naortic bulb: a model study. \u003Cspan class=\u0022cit-source\u0022\u003EAm. J. Physiol\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E240\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003ER200\u003C\/span\u003E\n-R210.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-7-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-7\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.7\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EClark, R. J. and Rodnick, K. I.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1999\u003C\/span\u003E).\nPressure and volume overloads are associated with ventricular hypertrophy in\nmale rainbow trout. \u003Cspan class=\u0022cit-source\u0022\u003EAm. J. Physiol\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E277\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003ER938\u003C\/span\u003E\n-R946.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-8-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-8\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.8\u0022 data-doi=\u002210.1002\/jez.1402090120\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EFarrell, A. P.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1979\u003C\/span\u003E). The Windkessel effect of\nthe bulbus arteriosus in trout. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Zool\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E209\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E169\u003C\/span\u003E\n-173.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BExp.%2BZool%26rft.volume%253D209%26rft.spage%253D169%26rft_id%253Dinfo%253Adoi%252F10.1002%252Fjez.1402090120%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1002\/jez.1402090120\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1979HC44200019\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-9-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-9\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.9\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EFung, Y. C.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1981\u003C\/span\u003E). \u003Cspan class=\u0022cit-source\u0022\u003EBiomechanics:\nMechanical Properties of Living Tissues\u003C\/span\u003E. New York:\nSpringer-Verlag.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-10-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-10\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.10\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EJones, D. R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1970\u003C\/span\u003E). Experiments on ampihibian\nrespiratory and circulatory systems. \u003Cspan class=\u0022cit-source\u0022\u003EExp. Physiol.\nBiochem\u003C\/span\u003E. \u003Cspan class=\u0022cit-vol\u0022\u003E3\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E233\u003C\/span\u003E\n-293.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-11-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-11\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.11\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EJones, D. R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1991\u003C\/span\u003E). Cardiac energetics and the\ndesign of vertebrate arterial systems. In \u003Cspan class=\u0022cit-source\u0022\u003EEfficiency and Economy in\nAnimal Physiology\u003C\/span\u003E (ed. R. W. Blake), pp.\u003Cspan class=\u0022cit-fpage\u0022\u003E159\u003C\/span\u003E\n-168. Cambridge: Cambridge University\nPress.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-12-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-12\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.12\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EJones, D. R.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1999\u003C\/span\u003E). The teleost bulbus\narteriosus: form and functions. In \u003Cspan class=\u0022cit-source\u0022\u003EIcthyology: Recent Research\nAdvances\u003C\/span\u003E (ed. D. N. Saksena), pp.\u003Cspan class=\u0022cit-fpage\u0022\u003E111\u003C\/span\u003E\n-116. New Delhi: Oxford and IBH Publishing\nCo.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-13-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-13\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.13\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EJones, D. R., Langille, B. L., Randall, D. J. and Shelton,\nG.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1974\u003C\/span\u003E). Blood flow in dorsal and ventral aortas of the\ncod, \u003Cem\u003EGadus morhua\u003C\/em\u003E. \u003Cspan class=\u0022cit-source\u0022\u003EAm. J. Physiol\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E226\u003C\/span\u003E, \u003Cspan class=\u0022cit-fpage\u0022\u003E90\u003C\/span\u003E-95.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DAmerican%2BJournal%2Bof%2BPhysiology%2B--%2BLegacy%2BContent%26rft.stitle%253DAm%2BJ%2BPhysiol%26rft.issn%253D0002-9513%26rft.aulast%253DJones%26rft.auinit1%253DD.%26rft.volume%253D226%26rft.issue%253D1%26rft.spage%253D90%26rft.epage%253D95%26rft.atitle%253DBlood%2Bflow%2Bin%2Bdorsal%2Band%2Bventral%2Baortas%2Bof%2Bthe%2Bcod%252C%2BGadus%2Bmorhua%26rft_id%253Dinfo%253Apmid%252F4809892%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6MzoiUERGIjtzOjExOiJqb3VybmFsQ29kZSI7czo5OiJhanBsZWdhY3kiO3M6NToicmVzaWQiO3M6ODoiMjI2LzEvOTAiO3M6NDoiYXRvbSI7czoyNDoiL2pleGJpby8yMDYvMTkvMzMyNy5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-14-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-14\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.14\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EJones, D. R., Brill, R. W. and Bushnell, P. G.\u003C\/strong\u003E\n(\u003Cspan class=\u0022cit-pub-date\u0022\u003E1993\u003C\/span\u003E). Ventricular and arterial dynamics of anaesthetised and\nswimming tuna. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp. Biol.\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E182\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E97\u003C\/span\u003E\n-112.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DJones%26rft.auinit1%253DD.%2BR.%26rft.volume%253D182%26rft.issue%253D1%26rft.spage%253D97%26rft.epage%253D112%26rft.atitle%253DVENTRICULAR%2BAND%2BARTERIAL%2BDYNAMICS%2BOF%2BANAESTHETISED%2BAND%2BSWIMMING%2BTUNA%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjg6IjE4Mi8xLzk3IjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA2LzE5LzMzMjcuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-15-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-15\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.15\u0022 data-doi=\u002210.1016\/0300-9629(73)90122-9\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ELicht, J. H. and Harris, W. S.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1973\u003C\/span\u003E). The\nstructure, composition and elastic properties of the teleost bulbus arteriosus\nin the carp, \u003Cem\u003ECyprinius carpio\u003C\/em\u003E. \u003Cspan class=\u0022cit-source\u0022\u003EComp. Biocem. Physiol.\nA\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E46\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E699\u003C\/span\u003E\n-670.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DComp.%2BBiocem.%2BPhysiol.%250AA%26rft.volume%253D46%26rft.spage%253D699%26rft_id%253Dinfo%253Adoi%252F10.1016%252F0300-9629%252873%252990122-9%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1016\/0300-9629(73)90122-9\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-16-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-16\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.16\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EMcDonald, D. A.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1974\u003C\/span\u003E). \u003Cspan class=\u0022cit-source\u0022\u003EBlood Flow\nin Arteries.\u003C\/span\u003E Second edition. Baltimore: Williams and\nWilkins.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-17-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-17\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.17\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EMott, J. C.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1950\u003C\/span\u003E). Radiological observations\non the cardiovascular system in \u003Cem\u003EAnguilla anguilla\u003C\/em\u003E. \u003Cspan class=\u0022cit-source\u0022\u003EJ. Exp.\nBiol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E27\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E324\u003C\/span\u003E\n-333.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJournal%2Bof%2BExperimental%2BBiology%26rft.stitle%253DJ.%2BExp.%2BBiol.%26rft.issn%253D0022-0949%26rft.aulast%253DMOTT%26rft.auinit1%253DJ.%2BC.%26rft.volume%253D27%26rft.issue%253D3%26rft.spage%253D324%26rft.epage%253D333%26rft.atitle%253DRadiological%2BObservations%2Bon%2Bthe%2BCardiovascular%2BSystem%2Bin%2BAnguilla%2BAnguilla%26rft_id%253Dinfo%253Apmid%252F14803616%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/ijlink\/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiamV4YmlvIjtzOjU6InJlc2lkIjtzOjg6IjI3LzMvMzI0IjtzOjQ6ImF0b20iO3M6MjQ6Ii9qZXhiaW8vMjA2LzE5LzMzMjcuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-ijlink\u0022\u003E\u003Cspan\u003E\u003Cspan class=\u0022cit-reflinks-abstract\u0022\u003EAbstract\u003C\/span\u003E\u003Cspan class=\u0022cit-sep cit-reflinks-variant-name-sep\u0022\u003E\/\u003C\/span\u003E\u003Cspan class=\u0022cit-reflinks-full-text\u0022\u003E\u003Cspan class=\u0022free-full-text\u0022\u003EFREE \u003C\/span\u003EFull Text\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-18-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-18\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.18\u0022 data-doi=\u002210.1111\/j.1095-8649.1976.tb04674.x\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EPriede, I. G.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1976\u003C\/span\u003E). Functional morphology of\nthe bulbus arteriosus of rainbow trout (\u003Cem\u003ESalmo gairdneri\u003C\/em\u003E Richardson).\n\u003Cspan class=\u0022cit-source\u0022\u003EJ. Fish Biol\u003C\/span\u003E. \u003Cspan class=\u0022cit-vol\u0022\u003E9\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E209\u003C\/span\u003E\n-216.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DJ.%2BFish%2BBiol%26rft.volume%253D9%26rft.spage%253D209%26rft_id%253Dinfo%253Adoi%252F10.1111%252Fj.1095-8649.1976.tb04674.x%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1111\/j.1095-8649.1976.tb04674.x\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-19-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-19\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.19\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ERandall, D. J.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1968\u003C\/span\u003E). Functional morphology of\nthe heart in fishes. \u003Cspan class=\u0022cit-source\u0022\u003EAm. Zool\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E8\u003C\/span\u003E, \u003Cspan class=\u0022cit-fpage\u0022\u003E179\u003C\/span\u003E-189.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DAmerican%2BZoologist%26rft.stitle%253DAmerican%2BZoologist%26rft.aulast%253DRandall%26rft.auinit1%253DD.%2BJ.%26rft.volume%253D8%26rft.issue%253D2%26rft.spage%253D179%26rft.epage%253D189%26rft.atitle%253DFunctional%2Bmorphology%2Bof%2Bthe%2Bheart%2Bin%2Bfishes.%26rft_id%253Dinfo%253Apmid%252F5738636%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=5738636\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F206%2F19%2F3327.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=A1968B420700001\u0026amp;link_type=ISI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-newisilink cit-ref-sprinkles-webofscience\u0022\u003E\u003Cspan\u003EWeb of Science\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-20-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-20\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.20\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ESanter, R. M.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1985\u003C\/span\u003E). Morphology and\ninnervation of the fish heart. \u003Cspan class=\u0022cit-source\u0022\u003EAdv. Anat. Embryol. Cell\nBiol.\u003C\/span\u003E \u003Cspan class=\u0022cit-vol\u0022\u003E89\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E1\u003C\/span\u003E\n-102.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DAdvances%2Bin%2BAnatomy%252C%2BEmbryology%252C%2Band%2BCell%2BBiology%26rft.stitle%253DAdvances%2Bin%2BAnatomy%252C%2BEmbryology%252C%2Band%2BCell%2BBiology%26rft.aulast%253DSanter%26rft.auinit1%253DR.%2BM.%26rft.volume%253D89%26rft.spage%253D1%26rft.epage%253D102%26rft.atitle%253DMorphology%2Band%2Binnervation%2Bof%2Bthe%2Bfish%2Bheart.%26rft_id%253Dinfo%253Apmid%252F3890474%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=3890474\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F206%2F19%2F3327.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-21-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-21\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.21\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003ESatchell, G. H.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1971\u003C\/span\u003E). \u003Cspan class=\u0022cit-source\u0022\u003ECirculation\nin Fishes\u003C\/span\u003E. Cambridge: Cambridge University Press.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-22-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-22\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.22\u0022 data-doi=\u002210.1016\/0300-9629(72)90255-1\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EStevens, E. D., Bennion, G. R., Randall, D. J. and Shelton,\nG.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1972\u003C\/span\u003E). Factors affecting arterial pressures and blood\nflow from the heart in intact, unrestrained lingcod, \u003Cem\u003EOphiodon\nelongatus\u003C\/em\u003E. \u003Cspan class=\u0022cit-source\u0022\u003EComp. Biochem. Physiol. A\u003C\/span\u003E\n\u003Cspan class=\u0022cit-vol\u0022\u003E43\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E681\u003C\/span\u003E\n-695.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DComp.%2BBiochem.%2BPhysiol.%2BA%26rft.volume%253D43%26rft.spage%253D681%26rft_id%253Dinfo%253Adoi%252F10.1016%252F0300-9629%252872%252990255-1%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=10.1016\/0300-9629(72)90255-1\u0026amp;link_type=DOI\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-doi cit-ref-sprinkles-crossref\u0022\u003E\u003Cspan\u003ECrossRef\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-23-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-23\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.23\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003Evon Skramlick, E.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1935\u003C\/span\u003E). \u00dcber der\nkreislauf bei den fischen. \u003Cspan class=\u0022cit-source\u0022\u003EErgbn. Biol\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E11\u003C\/span\u003E, \u003Cspan class=\u0022cit-fpage\u0022\u003E1\u003C\/span\u003E-30.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003Cli\u003E\u003Cspan class=\u0022ref-label ref-label-empty\u0022\u003E\u003C\/span\u003E\u003Ca class=\u0022rev-xref-ref\u0022 href=\u0022#xref-ref-24-1\u0022 title=\u0022View reference in text\u0022 id=\u0022ref-24\u0022\u003E\u21b5\u003C\/a\u003E\n \u003Cdiv class=\u0022cit ref-cit ref-other\u0022 id=\u0022cit-206.19.3327.24\u0022\u003E\u003Cdiv class=\u0022cit-metadata\u0022\u003E\u003Ccite\u003E\u003Cstrong\u003EWatson, A. D. and Cobb, J. L. S.\u003C\/strong\u003E (\u003Cspan class=\u0022cit-pub-date\u0022\u003E1979\u003C\/span\u003E). A\ncomparative study on the innervation and vascularization of the bulbus\narteriosus in the teleost fish. \u003Cspan class=\u0022cit-source\u0022\u003ECell Tissue Res\u003C\/span\u003E.\n\u003Cspan class=\u0022cit-vol\u0022\u003E196\u003C\/span\u003E,\u003Cspan class=\u0022cit-fpage\u0022\u003E337\u003C\/span\u003E\n-346.\u003C\/cite\u003E\u003C\/div\u003E\u003Cdiv class=\u0022cit-extra\u0022\u003E\u003Ca href=\u0022{openurl}?query=rft.jtitle%253DCell%2Band%2Btissue%2Bresearch%26rft.stitle%253DCell%2BTissue%2BRes%26rft.aulast%253DWatson%26rft.auinit1%253DA.%2BD.%26rft.volume%253D196%26rft.issue%253D2%26rft.spage%253D337%26rft.epage%253D346%26rft.atitle%253DA%2Bcomparative%2Bstudy%2Bon%2Bthe%2Binnervation%2Band%2Bthe%2Bvascularization%2Bof%2Bthe%2Bbulbus%2Barteriosus%2Bin%2Bteleost%2Bfish.%26rft_id%253Dinfo%253Apmid%252F421260%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-openurl cit-ref-sprinkles-open-url\u0022\u003E\u003Cspan\u003EOpenUrl\u003C\/span\u003E\u003C\/a\u003E\u003Ca href=\u0022\/lookup\/external-ref?access_num=421260\u0026amp;link_type=MED\u0026amp;atom=%2Fjexbio%2F206%2F19%2F3327.atom\u0022 class=\u0022cit-ref-sprinkles cit-ref-sprinkles-medline\u0022\u003E\u003Cspan\u003EPubMed\u003C\/span\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\n \u003C\/li\u003E\u003C\/ol\u003E\u003C\/div\u003E\u003Cspan class=\u0022highwire-journal-article-marker-end\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Cspan id=\u0022related-urls\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Ca href=\u0022http:\/\/jeb.biologists.org\/content\/206\/19\/3327.abstract\u0022 class=\u0022hw-link hw-link-article-abstract\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EView Abstract\u003C\/a\u003E\u003C\/div\u003E \u003C\/div\u003E\n\n \n \u003C\/div\u003E\n\u003Cdiv class=\u0022panel-separator\u0022\u003E\u003C\/div\u003E\u003Cdiv class=\u0022panel-pane pane-highwire-article-trendmd\u0022 \u003E\n \n \n \n \u003Cdiv class=\u0022pane-content\u0022\u003E\n \u003Cdiv id=\u0022trendmd-suggestions\u0022\u003E\u003C\/div\u003E \u003C\/div\u003E\n\n \n \u003C\/div\u003E\n\u003C\/div\u003E\n \u003C\/div\u003E\n\u003C\/div\u003E\n\u003C\/div\u003E\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/jeb.biologists.org\/sites\/default\/files\/js\/js_pIbxCkwqLFhe06EWMX4fv7eYg7RhKB6h_Vj4CPMFqWI.js\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022 defer=\u0022defer\u0022 src=\u0022http:\/\/jeb.biologists.org\/sites\/all\/libraries\/lazysizes\/lazysizes.min.js?pd9lw1\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/jeb.biologists.org\/sites\/default\/files\/js\/js_7RMjx5FIDm_47i-AM0smRZ6fDP1CFPb9z_oiSLz90Gc.js\u0022\u003E\u003C\/script\u003E\n\u003C\/body\u003E\u003C\/html\u003E"}